Solid State Phenomena Vols. 181-182

Abstract: The liquid crystalline compounds viz, N-(p-n-decyloxybenzylidene)-p-n-octadecyl aniline, 10O.18, N-(p-n-octadecyloxybenzylidene)-p-n-octadecylaniline, 18O.18, (p-n-biphenylbenzylidene) -p-n-octadecylaniline, PB18A and terephthalyidene-bis-p-n-octadecylaniline, TB18A have been synthesized for the first time and the characterization is carried out using thermal microscopy (TM) attached with a hot stage and differential scanning calorimeter (DSC). All the four compounds exhibit a variety of phase variants such as isotropic to smectic-F (Iso-SmF) in 10O.18, isotropic to smectic-F (Iso-SmF) in 18O.18, isotropic to smectic-A to smectic-B (SmA-SmB) in PB18A and isotropic to smectic-C to smectic-I to smectic-F (Iso-SmC-SmI-SmF) in TB18A.

Abstract: A hexa-peri-hexabenzocoronene (HBC) derivative, substituted at periphery by six swallow-tailed alkyl chains containing ether linkages, has been synthesized. Its thermal properties and self-organization were investigated using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Results showed that the peripheral side chains substituted to the aromatic core could lead the HBC to a dramatically lowered isotropization temperature compared with those reported previously, allowing thermal processing at practical temperatures.

Abstract: Thermal properties and phase behavior of series of main chain copolymers containing oligomeric-L-LA segments (OLLA) and biphenol groups were synthesized and characterized. OLLA segments were prepared by ring opening polymerization of L-LA initiated by biphenol mesogens with active HO-group and then polymerized to form main chain polymer by the reaction pentanedioyl dichloride with the-OH groups at the free end of OLLA. Their phase behaviors were studied by using DSC and POM. XRD measurements revealed the formation of layered structures. CD measurements were used to measure the helical structure and the optical rotation power of the main chain polymers.

Abstract: A novel triphenylene-based discotic liquid crystal compound 2-(8-bromooctanoic acid ester)-3,6,7,10,11-penta-pentyloxytriphenylene was synthesized in this study.The chemical structure of the compound was characterized by ¹HNMR spectra, FT-IR spectra and we confirmed its structure. The mesophases were investigated by using different scanning calorimetry DSC and polarizing optical microscopy POM, the results showed that the target product had Liquid crystal properties and the temperature range of 90-101 °C, and showed a clear columnar phase. The carrier transport mobility was measured using time-of-flight TOF method, μ=1.09*10^-2cm²V^-1s^-1.

Abstract: In this article, the phase morphology and mechanical properties of poly (trimethylene terephthalate)/maleinized poly (octene-ethylene) copolymer blends are studied by using scanning electron microscopy (SEM), polarized optical microscopy (POM), universal material tester and charpy impact tester. The results suggest that the crystal size of the blends decreases obviously and POE component is partly served as nucleating agent for the crystallization of PTT. PTT and POE have good compatibility in blends because the dispersed phase of POE has even dispersion in blends when POE content is lower than 5%; however, the dispersion state of POE becomes poor when POE content is larger than 5%. The impact strength increases to maximum when the POE content is about 4 %. The tensile strength gets to maximum when POE content is 1-2 %.

Abstract: In this paper, (E)-4-(2-(4-(allyloxy) phenyl) diazenyl) benzoic acid and (E)-4-(2-(4-(hexyloxy) phenyl) diazenyl) benzoic acid were synthesized through diazotize-coupling reaction and etherification. The structures of these compounds were characterized by the methods of 1H-NMR and FTIR. Phase transition temperature was measured by DSC, and the phase behaviors were studied by the polarizing microscope. Both of them had mesomorphic phase. And the mesophase temperature of (E)-4-(2-(4-(hexyloxy) phenyl) diazenyl) benzoic acid ranged from 224.9 °C to 265.4 °C.

Abstract: A rod-like liquid crystal (LC) N,N-(terephthalylidene) bis (4-n-butylaniline) (TB4A) was synthesized by one step at room temperature. The synthesized TB4A were investigated with nuclear magnetic resonance, fourier transform infrared spectrometer and ultraviolet-visible spectrophotometry, differential scanning calorimetry and polarizing optical microscopy. Our results demonstrated that the TB4A can form nematic, smectic A, smectic C, smectic F and smectic G LC phases.

Abstract: In this paper, a novel protocol of akylation to tolan using CuI/HMPA as catalyst for synthesizing alkyl-substituted hexabenzocoronene (HBC) was described. The key step in the route was the construction of tolan bearing 2 long side chains, which was completed in the first step via coupling reaction between 4, 4’-Bis (bromomethyl) tolan (1) and Grignard Reagent in a mild condition. Afterward, Co₂(CO)₈ catalyzed cyclotrimerization gave hexaphenylbenzene derivative (HPB) which could be easily separated by column chromatography and recrystalization. The planarization of HPB was carried out with FeCl₃ /MeNO₂ to afford the desired HBC with long odd-carbon alkyl chains in good overall yields.

Abstract: Novel polyfluorene derivatives with azobenzene moieties to attaching to the polymer backbone via a flexible alkyl spacer were synthesized by electrochemically direct anodic oxidation in boron trifluoride diethyletherate (BFEE). The physical, optical and fluorescent properties of the synthesized polymers were characterized by UV-vis spectroscopy and fluorescent spectroscopy. As conducting and optical materials, these polymers can be promising in the field of photoelecrtonics area.

Abstract: Two kinds of novel unsymmetric imidazolium salts based ionic liquid crystals (1- [4-(dodecyloxy) phenyl]-3-hexyl/octyl-1H-imidazol-3-ium bromide) were efficiently prepared using a microwave-assisted method. Their mesomorphism has been fully investigated by POM and DSC. The two imidazolium salts displayed typical and good smectic phase textures.